Hydrogen detachment of the hexahydrated hydroiodic acid upon attaching an excess electron.

A hydroiodic acid molecule is dissociated by more than four water molecules. Here, the effect of an excess electron on the hexahydated hydroiodic acid where the dissociated structure [H3O+(H2O)5I-] is much more stable than the undissociated one [(H2O)6HI], is investigated. Upon binding an excess electron (e-), the cluster releases a hydrogen radical and forms the stable hexahydrated iodide [(H2O)6I-] when the initial kinetic energy is above ∼200 K, due to the small transition barrier (∼0.5 eV). The system with the hydrogen radical released, [(H2O)6I- + H·], is much more stable than the systems with an excess electron, [(H3O)+{e-(H2O)5}I-] or [e-(H2O)2(H3O)+(H2O)3I-]. [ABSTRACT FROM AUTHOR]